Membrane domains and flagellar pocket boundaries are influenced by the cytoskeleton in African trypanosomes

A key feature of immune evasion for African trypanosomes is the functional specialization of their surface membrane in an invagination known as the flagellar pocket (FP), the cell''s sole site of endocytosis and exocytosis. The FP membrane is biochemically distinct yet continuous with those of the cell body and the flagellum. The structural features maintaining this individuality are not known, and we lack a clear understanding of how extracellular components gain access to the FP. Here, we have defined domains and boundaries on these surface membranes and identified their association with internal cytoskeletal features. The FP membrane appears largely homogeneous and uniformly involved in endocytosis. However, when endocytosis is blocked, receptor-mediated and fluid-phase endocytic markers accumulate specifically on membrane associated with four specialized microtubules in the FP region. These microtubules traverse a distinct boundary and associate with a channel that connects the FP lumen to the extracellular space, suggesting that the channel is the major transport route into the FP.     

Focal adhesion kinase is a blood–testis barrier regulator

In mammalian testes, such as rats, the mechanism(s) that regulate blood–testis barrier (BTB) restructuring at stages VIII–IX of the seminiferous epithelial cycle of spermatogenesis to facilitate the transit of preleptotene/leptotene spermatocytes is not known. This is due to the lack of information on the regulatory proteins at the BTB. Herein, focal adhesion kinase (FAK), a nonreceptor protein tyrosine kinase, is shown to structurally interact with occludin and ZO-1 to form a functional protein complex at the BTB. Its expression at the BTB in the seminiferous epithelium is stage specific, being lowest at stage VIII–IX tubules, analogous to the expression pattern of occludin. Using primary Sertoli cells cultured in vitro with an established tight junction (TJ) permeability barrier that mimics the BTB in vivo, the knockdown of FAK by RNAi led to a transient disruption of the TJ barrier. This was accompanied by a loss of association between occludin and ZO-1, likely the result of reduced occludin phosphorylation at Tyr and Ser residues, but not Thr, which in turn led to a redistribution of occludin at the Sertoli–Sertoli cell interface, moving from cell membrane into cell cytosol, thereby disrupting the BTB. These findings suggest that a similar mechanism is in place in the testis in vivo to regulate BTB restructuring to facilitate the transit of primary spermatocytes. Furthermore, FAK was shown to be a molecular target of cadmium because its knockdown would desensitize Sertoli cells to cadmium-induced TJ barrier disruption. In summary, FAK is a unique regulator of BTB dynamics in the testis.     

Non-verbal communication; reflections on body language

The present study aimed to reflect on the importance of body language through the identification of what a graduate nursing group knew about this topic. We analyzed the contents of reports from which five categories emerged: concept, function, importance, meaning and forms of body language manifestation. The group valued body language as a complex way of interpersonal interaction that sometimes occurs out of our control and of which we have little conscience. It has the function of expressing feelings, emotions and transmitting messages whose meanings are influenced by context. Body language knowledge increases our professional perception and it is one more instrument to improve nursing assistance quality.     

Synthetic derivatives of curcumin and their activity against Leishmania amazonensis

In a previous work, the in vitro and in vivo activity of a series of diarylheptanoid derivatives against Leishmania amazonensis has been described. Based on the promising results, ten new compounds belonging to the same chemical class were synthesized and have been investigated in relation to their leishmanicidal activity. The compounds were obtained through several chemical modifications on the basic structure of curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) in an attempt to increase its effectiveness and decrease the potential toxic effects. The drugs were assayed in vitro against L. amazonensis promastigotes and using pentamidine isethionate as reference drug. The results showed that the most effective compound is 1,7-bis-(4-propargyl-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, which is about ten times more efficient than the original curcumin. Nevertheless, these results did not allow us to make any correlation between the leishmanicidal activity and the chemical structure of the compounds.     

A curriculum for training quality scholars to improve the health and health care of veterans and the community at large

In 1998, the Veterans Health Administration invested in the creation of the Veterans Administration National Quality Scholars Fellowship Program (VAQS) to train physicians in new ways to improve the quality of health care. We describe the curriculum for this program and the lessons learned from our experience to date. The VAQS Fellowship program has developed a core improvement curriculum to train postresidency physicians in the scholarship, research, and teaching of the improvement of health care. The curriculum covers seven domains of knowledge related to improvement: health care as a process; variation and measurement; customer/beneficiary knowledge; leading, following, and making changes in health care; collaboration; social context and accountability; and developing new, locally useful knowledge. We combine specific knowledge about the improvement of health care with the use of adult learning strategies, interactive video, and development of learner competencies. Our program provides insights for medical education to better prepare physicians to participate in and lead the improvement of health care.     

Transducing system operated by adenosine A(2A) receptors to facilitate acetylcholine release in the rat hippocampus

In spite of the increasing evidence concerning its neurotoxicity, young human individuals are often involved in the recreational use of amphetamine-type stimulants such as 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy"). A study aimed to investigate short- and long-term consequences of a repeated and intermittent MDMA administration (0, 5 or 10 mg/kg i.p., 3 days treatment history) was conducted in mice. Mice were injected at different phases in development, namely at early (28 days old), middle (38 days old) or late (52 days old) adolescence. When assessed for nociceptive response, a dose-dependent analgesia was found in middle and late adolescent mice. Carryover consequences of previous MDMA treatment were then investigated at adulthood (80 days old). In a social interaction test, levels of environment exploration and social behaviour resulted markedly increased in drug-free state as a function of drug exposure during development, whereas others behaviours were reduced. MDMA challenge (5-mg/kg dose) produced the expected hyperactivity, as well as a marked increment of hypothalamic serotonin (5-hydroxyhyptamine, 5-HT) levels. Mice treated chronically with MDMA during middle and late adolescence were associated with important reductions of the indoleamine. As a whole, these results indicate a differential long-term vulnerability to behavioural and neurotoxicant effects of MDMA as a function of the developmental stage of exposure.     

Treating depression in Alzheimer disease: efficacy and safety of sertraline therapy,and the benefits of depression reduction: the DIADS

CONTEXT: Major depression affects about 25% of the patients who have Alzheimer disease and has serious adverse consequences for patients and caregivers. Results of prior antidepressant treatment studies have produced contradictory findings and have not fully assessed the benefits of depression reduction. OBJECTIVES: To assess the efficacy and safety of sertraline hydrochloride for the treatment of major depression in Alzheimer disease, and to evaluate the effect of depression reduction on activities of daily living, cognition, and nonmood behavioral disturbance. DESIGN: Randomized, placebo-controlled, parallel, 12-week, flexible-dose clinical trial with a 1-week, single-blind placebo phase. The study was conducted between January 1, 1998, and July 19, 2001. SETTING: University outpatient clinic. PARTICIPANTS: Forty-four outpatients who have probable Alzheimer disease and major depressive episodes. INTERVENTION: Sertraline hydrochloride, mean dosage of 95 mg/d, or identical placebo, randomly assigned. MAIN OUTCOME MEASURES: Response rate, Cornell Scale for Depression in Dementia, Hamilton Depression Rating Scale, Mini-Mental State Examination, Psychogeriatric Depression Rating Scale-activities of daily living subscale, and Neuropsychiatric Inventory to quantify patient behavior disturbance and caregiver distress. RESULTS: In the sertraline-treated group 9 patients (38%) were full responders and 11 (46%) were partial responders compared with 3 (20%) and 4 (15%), respectively, in the placebo-treated group (P =.007). The sertraline-treated group had greater improvements in the scores for the Cornell Scale for Depression in Dementia (P =.002) and Hamilton Depression Rating Scale (P =.01), and a statistical trend toward less decline in activities of daily living on the Psychogeriatric Depression Rating Scale-activities of daily living subscale (P =.07). There was no difference between the treatment groups in Mini-Mental State Examination (P =.22) or Neuropsychiatric Inventory (P =.32) ratings over time. When full responders, partial responders, and nonresponders were compared, full responders only, or full and partial responders had significantly better ratings on activities of daily living (P =.04), behavioral disturbance (P =.01), and caregiver distress (P =.006), but not on the Mini-Mental State Examination (P =.76). Safety monitoring indicated few differences in adverse effects between the 2 treatment groups. CONCLUSIONS: Sertraline is superior to placebo for the treatment of major depression in Alzheimer disease. Depression reduction is accompanied by lessened behavior disturbance and improved activities of daily living, but not improved cognition.     

Insulin affects synaptosomal GABA and glutamate transport under oxidative stress conditions

In this study, we investigated the in vitro effect of exogenously administered insulin on the susceptibility to oxidative stress and on the accumulation of the amino acid neurotransmitters gamma-aminobutyric acid (GABA) and glutamate in a synaptosomal fraction isolated from male Wistar rat brain cortex. Insulin (1 microM) did not affect synaptosomal lipid peroxidation induced by the oxidant pair ascorbate/Fe(2+), although under these conditions an increase in thiobarbituric acid reactive substances (TBARS) levels was observed. Under control conditions, the presence of insulin did not change the uptake of [3H]GABA or [3H]glutamate. In contrast, under oxidizing conditions, we observed a 1.8- and a 2.2-fold decrease in [3H]GABA and [3H]glutamate accumulation, respectively, and insulin reverted the lower levels of both [3H]GABA and [3H]glutamate accumulation (to 86.74+/-6.26 and 67.01+/-6.65% of control, respectively). Insulin also increased the extrasynaptosomal levels of GABA and glutamate, determined both in control and oxidizing conditions. From this study, we can conclude that insulin is a modulator of amino acid neurotransmitter transport, either directly, as seems to occur under normal conditions, or via the decrease in ATP levels and the subsequent reversion of the amino acid transporters, as seems to occur under oxidative stress conditions. The modulation of both GABA and glutamate transport might be implicated in the neuroprotective role of insulin.     

Subcellular localization of adenosine A(1) receptors in nerve terminals and synapses of the rat hippocampus

Adenosine is a neuromodulator in the CNS that mainly acts through pre- and postsynaptic A(1) receptors to inhibit the release of excitatory neurotransmitters and NMDA receptor function. This might result from a highly localized distribution of A(1) receptors in the active zone and postsynaptic density of CNS synapses that we now investigated in the rat hippocampus. The binding density of the selective A(1) receptor antagonist, [3H]1,3-dipropyl-8-cyclopentylxanthine ([3H]DPCPX), was enriched in membranes from Percoll-purified nerve terminals (B(max)=1839+/-52 fM/mg protein) compared to total membranes from the hippocampus (B(max)=984+/-31 fM/mg protein), the same occurring with A(1) receptor immunoreactivity. [3H]DPCPX binding occurred mainly to the plasma membrane rather than to intracellular sites, since the binding of the membrane permeable A(1) receptor ligand [3H]DPCPX to intact hippocampal nerve terminals (B(max)=1901+/-192 fM/mg protein) was markedly reduced (B(max)=321+/-30 fM/mg protein) by the membrane impermeable adenosine receptor antagonist, 8-sulfophenyltheophilline (25 microM). Further subcellular fractionation of hippocampal nerve terminals revealed that A(1) receptor immunoreactivity was strategically located in the active zone of presynaptic nerve terminals, as expected to understand the efficiency of A(1) receptors to depress neurotransmitter release. A(1) Receptors were also present in nerve terminals outside the active zone in accordance with the existence of a presynaptic A(1) receptor reserve. Finally, A(1) receptor immunoreactivity was evident in the postsynaptic density together with NMDA receptor subunits 1, 2A and 2B and with N-and P/Q-type calcium channel immunoreactivity, emphasizing the importance of A(1) receptors in the control of dendritic integration.